Tunable Terahertz plasmonic lens with external magnetic field

A tunable Terahertz (THz) plasmonic lens based on a micro-slit structure is proposed. The micro-slit structure is designed with InSb materials, the dielectric property of which in the THz frequency regime functions similar to metals in the optical frequency regime, and can be altered by an external magnetic field. Thus, for this micro-slit structure, the plasmonic effect can be explored in the THz regime and properties such as the phases of light through the micro-slits can be tuned. It is found that light passing through the well-designed micro-slits can be focused to a small-size spot and the tuning range of the focal length by the applied magnetic field is about 3λ.